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A researcher has disclosed a couple of serious Slack vulnerabilities that could have been exploited to obtain sensitive information and take over user accounts. The vendor patched the flaws and awarded the expert a total of $ 9,000.

According to researcher David Vieira-Kurz, Slack was affected by two access control bypass flaws that could have lead to some serious damage. The security holes were reported and fixed in April.

The expert first identified a misconfiguration issue related to the use of a module that allows administrators to obtain server status information, including which IP accessed which resource.

While initially this did not seem like a high-risk problem, Vieira-Kurz soon discovered that even unauthenticated users could request the server status, potentially giving them access to sensitive information associated with any Slack website. Slack awarded the researcher $ 2,000 for reporting this bug.

The second vulnerability identified by Vieira-Kurz was far more serious. The issue is related to a backend administration panel that allows Slack employees to obtain information on users and workspaces based on an ID.

The researcher determined that an attacker could use this to reset the password of any user by guessing their ID. The white hat hacker earned $ 7,000 for this report, which still hasn’t been publicly disclosed by Slack on its HackerOne page.

Through its bug bounty program, Slack offers researchers a minimum of $ 50 for low severity flaws and at least $ 1,500 for critical issues. Since the launch of its bug bounty program, the company resolved more than 500 reports and paid out a total of $ 180,000.

Slack is a highly useful team collaboration tool that allows users to create bots that help them automate certain tasks, including project management bots and various types of reminder bots. However, experts warned in April that many developers unwittingly included authentication tokens for Slack accounts in projects shared on GitHub.

A GitHub search revealed hundreds of tokens that could have been leveraged to access potentially sensitive information, including database credentials, logins for internal services and private messages.

An advisory published by VMware on Thursday describes two important vulnerabilities that affected several of the company’s products.

The first security hole, tracked as CVE-2016-5330, is a DLL hijacking issue in the Windows version of VMware Tools. The flaw can be exploited to execute arbitrary code on the targeted system.

The vulnerability was reported to VMware late last year by Yorick Koster, researcher and co-founder of Dutch security firm Securify. Koster told SecurityWeek that the issue was addressed by the vendor in April, but it was not disclosed until now to give users enough time to patch.

According to Koster, the flaw is related to the VMware Host Guest Client Redirector component of VMware Tools. The component is used for the Shared Folders feature, which allows users to share files between the guest and the host operating system.

The researcher noticed that when a document is opened from a uniform naming convention (UNC) path, the Client Redirector injects a DLL named “vmhgfs.dll” into the application that is used to open the file. Since the DLL was loaded from a relative path, Windows searched for it using the dynamic-link library search order.

This allowed an attacker to place a malicious DLL in a location from where it would likely be loaded before the legitimate file. By getting the Client Redirector to load the malicious DLL into the application, an attacker could have executed arbitrary code with the privileges of the targeted user. An attack could have resulted in the system getting completely compromised.

For the attack to work, the hacker needed to trick the victim into opening any document from the share containing the malicious DLL file. The researcher also believes the attack could have been launched over the Internet if the WebDAV Mini-Redirector was enabled.

Mini-Redirector is a Windows WebDAV client that allows users to access remote shares over the Internet as if they were on the local network. An attacker could have created their own malicious website with WebDAV enabled and use it to host bait documents and the malicious DLL. The vulnerability could have been exploited by luring the victim to the malicious website and getting them to open one of the documents.

Koster said VMware addressed the vulnerability by ensuring that the DLL is loaded from an absolute path. The flaw affects VMware vSphere Hypervisor (ESXi), Workstation Player and Pro, and Fusion.

Another vulnerability disclosed on Thursday by VMware is an HTTP header injection issue affecting vCenter Server and ESXi. The flaw, caused by lack of input validation, allows an attacker to set arbitrary HTTP response headers and cookies, and launch cross-site scripting (XSS) or malicious redirect attacks.

The security hole, tracked as CVE-2016-5331, was reported to VMware independently by several researchers.